A drum-type washing machine is a machine that washes laundry using detergent and water in a drum by rotating the drum using a driving force from a motor. This drum-type washing machine has advantages that it causes less damage to the laundry, the laundry is not frequently tangled, and the amount of water use is small.
Recently, a drum-type washing machine-cum-dryer has been widely used, which allows the laundry to be dried by blowing hot air into a drum through a drying duct. This drum-type washing machine-cum-dryer washes laundry while optionally or sequentially performing a washing cycle, a rinsing cycle, a dehydrating cycle, a drying cycle, and the like.
FIG. 1 illustrates a side cross-sectional view schematically showing a main structure of a conventional drum-type washing machine-cum-dryer.
Referring to FIG. 1, a drum-type washing machine is generally configured to include a cabinet 10 having a laundry loading opening formed on the front side thereof, a door 11 installed at the laundry loading opening of the cabinet 10 to be opened and closed, a tub 20 installed inside the cabinet 10 to hold washing water, a drum 22 rotatably installed in the tub 20, and a motor 50 installed on the tub 20 to transmit a driving force to the drum 22.
The drum-type washing machine is also provided with a drying duct 60 and a condensing duct 70 which are adapted to circulate air for a drying cycle. A heater 63 and a blowing fan 67 are installed in the drying duct 60 so that hot air can be charged into the tub 20. The drying duct 60 and the condensing duct 70 are installed so as to communicate with each other, and to communicate with the inside of the drum 22. The tub 20 has an intake port formed thereon through which hot air is drawn via the drying duct 60, and an exhaust port through which air is discharged into the condensing duct 70. The condensing duct 70 is provided with a water supply nozzle 75 adapted to supply cooling water so as to allow moisture in the air to condense.
In the drum-type washing machine configured as described above, a washing cycle and a drying cycle are generally performed in the following manner.
The door 11 is opened by a user and the laundry is loaded into the drum 22. Then, the door 11 is closed to make the drum 22 airtight. When a washing cycle is started, a water supply device 15 supplies water. The supplied water is heated by a heater 17 and mixed with detergent in a detergent container 12, and then supplied into the tub 20, where the water flows into the drum 22 via through-holes to wet the laundry. Subsequently, the motor 50 is driven to rotate the drum 22 for a preset washing time, and then the dirty water in the tub 20 is drained outside the washing machine through a drain hose 83 by the action of a drain pump 80.
When a drying cycle is started, power is applied to the heater 63 and the blowing fan 67 in the drying duct 60 to generate hot air. The generated hot air flows into the drum 22 by guidance of the drying duct 60. The hot air in the drum 22 is converted into low temperature and high humidity air while heating the laundry to dryness, and the low temperature and high humidity air is discharged into the condensing duct 70 through the exhaust port of the tub 20. The low temperature and high humidity air supplied to the condensing duct 70 is condensed by the cooling water supplied via the water supply nozzle 75 to precipitate moisture. The thus-dried air again flows into the drying duct 60 by the blowing fan 67. A series of these processes is repeatedly performed to dry the laundry.
However, these washing and drying cycles involve the use of energy for heating water and air, and energy loss due to loss of condensation heat, etc., which inevitably results in use of a large amount of thermal energy and loss related thereto.
Since the drum-type washing machine has a relatively long washing time and high power consumption, multiple attempts have been made to reduce energy use and loss in the washing and drying cycles by increasing the energy efficiency of a heating device or a condensing device. However, limitations have been encountered with regard to saving energy through the efficiency increase of such devices.
In particular, recently, as the size of washing machines has become larger and emphasis has been made on the importance of environment-friendly products, there is a growing need to save energy.